The present invention relates in general to bellows type foldable still cameras, and in particular to a camera having a housing, a displaceable objective support, flexible bellows arranged between the housing and the support, and a control mechanism for displacing the support between a collapsed position and an operative extended position, the mechanism having two symmetrically arranged strut systems each including a pair of upper and lower strut links for reinforcing the bellows in its operative extended position.
Cameras of this kind are known in numerous modifications and are still in use at the present time. In most cases, the struts for the displaceable objective are located outside the bellows and when folding the camera the pairs of strut links have to be first unlocked by exerting a synchronous pressure against actuation handles provided on corresponding halves of the strut links in each pair. In doing so, the user is exposed to the danger that his or her fingertips will get squeezed between the pivotable links of the struts.
Known are also cameras having the strut system arranged inside the bellows. This arrangement has the advantage that the unsightly external collapsable struts are dispensed with and the danger of squeezing the fingers by the strut linkage is eliminated. Nonetheless, even in this prior art structure of foldable cameras, a synchronous or consecutive operation of two handles is still necessary; this manipulation is of no consequence in the case of small cameras but in large size cameras it may become very uncomfortable.
A certain handling simplification has been already achieved in foldable cameras for small film formats by providing spring-biased struts whereby the springs are tensioned when the camera is folded. Upon actuating, the locking mechanism of the closed camera, the movable objective part together with the bellows springingly extend into the operative position. This solution, however, is unsuitable for large format cameras where it causes enormous difficulties. Due to a relatively large volume of air enclosed by the bellows, there must be provided light-tight channels for introducing air into the bellows during the opening process whereby precautions must be taken that the bellows do not become unduly deformed before the pressure balance is attained. For this reason, this design has been used only for cameras having a small volume of its bellows.
The design of the strut linkage encounters particular difficulties in cameras for large format films such as instant film cameras where it is desired to keep a high ratio between the depth of the open camera and the corresponding dimension of the closed camera.